PURPOSE: To use a cylindrical composite metal pipe in a cold state and to perform the forming of a high pressure liquid body by pressurizing it in the pipe thereof by providing a necessary taper on the inner face of a pair of upper and lower dies.

CONSTITUTION: A composite metal pipe P is held by a die 10, the high pressure hose from a high pressure liquid body source is connected to a flange 6 in the state of sealing both ends of the pipe P by cover like bodies 4, 5, the high pressure liquid like body is pressurized for the specified time via a pressure hole 6a and formed in the necessary taper shape. Thereafter, the specific composite taper metal pipe is obtainable by cutting the unnecessary part. Consequently the composite taper metal pipe at low cost and of high quality can be formed, so the industrial effect thereof is big.